The present invention generally relates to antifoams for use in the paper industry. More specifically, the present invention relates to fatty alcohol antifoams with improved shelf life.
Foam is a material made up of gas bubbles separated from one another by films of liquid. Although foams of exceptional stability are desired in some commercial applications, foam is a nuisance in many situations. For instance, in the glue and paper industries, foams cause undesirable complications. A common recourse is the addition of chemical antifoams, which are sometimes insoluble liquids of very low surface tension. When a droplet of such a liquid is sprayed onto the foam or is carried into it by mechanical agitation, it spreads spontaneously and rapidly at the surface of the film, virtually sweeping the foam away as it does so. Liquids frequently used for this purpose are octyl alcohol, tributyl phosphate, silicone and many patented preparations.
Antifoams, such as fatty alcohol defoamers, thus serve a critical function in a variety of industries, such as the paper industry. However, a disadvantage of commercial antifoam formulations is their limited shelf-life. Known antifoams often cream during storage and in some cases thicken to such an extent that they can no longer be pumped. This thickening or gelation renders the application of the fatty alcohol active ingredient to a foaming system difficult at best, limiting the sale of products containing substantially the fatty alcohol active ingredient.
Moreover, another disadvantage of known antifoams is that they are ineffective at elevated temperatures. Antifoam emulsions, which are conventionally used in papermaking, are known to become less effective if the temperature of the aqueous system to be defoamed increases above 50.degree. C. At temperatures above 60.degree. C., an even more rapid decrease in the effectiveness of the antifoam occurs when known oil-in-water emulsions are used. Since an increasing tendency for water circulations in the paper mills is to be closed ones, the result is that the temperature of the water conveyed in the circulation increases during papermaking, so that the effectiveness of the antifoams used to date decreases substantially.
Therefore, a need exists for a fatty alcohol antifoam formulation with improved shelf life and improved elevated temperature performance.